This invention relates to a jet loom, in which weft yarns are inserted into a shed by a jet of fluid, and more particularly to a comb comprising teeth with apertures for guiding the insertion of the weft yarns.
In the jet loom of the type described above, the aperture in each tooth is formed in a substantially circular shape so as to surround the weft yarn during the insertion thereof, and has an opening allowing the weft yarn to come out of the aperture therethrough in preparation for the beating of the weft yarn. However, because the fluid injected into the apertures of the teeth is subject to escape from the openings, resulting in a greater consumption of the fluid and the failure of the weft insertion operation, a comb has been designed so as to normally close the openings and only open the same when the weft yarn passes through the openings.
For example, one such prior comb is known from Japanese published and examined patent specification No. 53-27394. This known comb comprises a number of longitudinally spaced teeth or guides 1, only one of which is shown in FIG. 1 for the purpose of simplification. The guide 1 comprises a bifurcated root portion, from which both a substantially straight part 2 and a curved part 3 extend upwardly with a substantially vertically extending opening 4 formed between the inner surface of the end of the straight part 2 and the end surface of the curved part 3. The curved part 3 on the inner surface of the end thereof is provided with a flexible tongue 5 extending toward the inner surface of the end of the straight part and across the opening 4 so as to normally close the opening 4. The guide 1 thus formed in turned downwardly with respect to an inserted weft yarn Y by a (not shown) conventional means so that the center of the aperture in each guide moves in a direction parallel to a line inclined at an angle .theta. with respect to a horizontal plane including the inserted weft yarn Y.
It will therefore be appreciated that, upon such movement of the guide 1, the weft yarn Y in the aperture of the guide moves relative to the guide 1, and first comes into contact with the root of the tongue 5 [FIG. 1(b)], and then slides on the tongue 5 toward the tip thereof until it bears against the inner surface of the straight part 2 [FIG. 1(c)]. Then, the weft yarn is turned upwardly to move out of the aperture of the guide through the opening 4 while making the tongue 5 bend. As shown in FIG. 1(c), when the weft yarn Y is in contact with the straight part 2, a force a applied to the weft yarn Y due to the movement of the guide 1 can be divided into a component b perpendicular to the inner surface of the straight part 2, and a component c extending along the inner surface of the straight part 2 and substantially perpendicular to the tongue 5. However, since the component c available to bend the tongue 5 is very small as compared with the component b, the tongue 5 can not be bent easily by the weft yarn Y. This means that the yarn Y is subjected to a great resistance when passing through the opening 4. This great resistance causes a number of small loops or kinks corresponding in number to the tongues 5 to be formed on the weft yarn Y, which has passed through the tongue 5. Such a looped yarn is exaggeratedly shown in FIG. 2, and a cloth woven from the above defective yarns will create a rough feeling.
It is therefore a principal object of this invention to provide a weft yarn guiding comb for a jet loom, in which a tongue can be bent easily by a weft yarn when the latter comes out of the comb, thus removing the disadvantages of the prior art.